As I mentioned earlier, it is very encouraging to receive many emails and phone calls from readers with questions about the application and installation requirements of the 2024 edition of the Canadian Electrical Code, Part I (CE Code), the 2020 edition of the National Building Code of Canada (NBC), and the relevant standards referenced in these codes.
This article compiles the six recent questions and their answers.
Question 1
What is the difference between a standby and a backup power supply?
Answer to question 1: A standby power supply, also called a backup power supply, is equipment that provides an alternative power source when the primary power supply fails. Although the CE Code does not use the term “backup” power source, it is similar to a “standby” power supply. The CE Code uses the term “standby” power sources in several rules and clarification notes in Appendix B.
A typical “standby” or “backup” power supply source can include various generators, batteries, energy storage systems, and uninterrupted power supply (UPS) equipment.
There is a difference, however, between a standby (or backup) power supply system and an emergency supply system. While the CE Code does not mandate the use of a standby power supply system but only provides installation requirements for such systems when they are used, Section 46 of the CE Code mandates the use of batteries or generators when such batteries or generators are specifically required by the NBC to serve as emergency power supply sources for life safety systems.
Section 46 of the CE Code offers the following provisions in this regard:
“46-000 Scope (see Appendix B)
1) This Section applies to the installation, operation, and maintenance of
a) emergency power supply and unit equipment intended to provide power to life safety systems; and
b) emergency power supply and unit equipment intended to provide illumination of exit signs, in the event of failure of the normal supply, where the emergency power supply is required by the National Building Code of Canada.
2) This Section applies to the wiring between the emergency power supply and life safety systems that are required by the National Building Code of Canada to be provided with an emergency power supply.
3) This Section applies to the wiring of exit signs.
4) The requirements of this Section supplement or amend the general requirements of this Code.
46-002 Special terminology (see Appendix B)
In this Section, the following definitions shall apply:
Emergency power supply — emergency power, supplied by a generator, batteries, or a combination thereof, that is required by the National Building Code of Canada.
Life safety systems — emergency lighting and fire alarm systems that are required to be provided with an emergency power supply from batteries, generators, or a combination thereof, and electrical equipment for building services such as fire pumps, elevators, smoke-venting fans, smoke control fans, and dampers that are required to be provided with an emergency power supply by an emergency generator in conformance with the National Building Code of Canada.
Unit equipment — unit equipment for emergency lighting conforming to CSA C22.2 No. 141.”
It is obvious from the definition “life safety systems” above, that the NBC recognizes batteries or generators for some types of life safety systems and mandates use of an emergency generator for types of life safety equipment such as elevators, smoke-venting fans, smoke control fans, and dampers in high buildings and for fire pumps, when electrically connected fire pumps are utilized in a building of any height.
Sentence 3.2.7.9.(1) of the NBC offers the list of life safety equipment that must be provided with the alternate power supply source from an emergency generator only, as follows:
“3.2.7.9. Emergency Power for Building Services
1) An emergency power supply capable of operating under a full load for not less than 2 h shall be provided by an emergency generator for
a) every elevator serving storeys above the first storey in a building that is more than 36 m high measured between grade and the floor level of the top storey and every elevator for firefighters in conformance with Sentence (2),
b) except as provided in Sentence (4), equipment that supplies water for fire suppression as required by Articles 3.2.5.7. and 3.2.5.8. and Sentences 3.2.5.12.(1) and (2) and 3.2.5.18.(1), if the supply depends solely on electrical power supplied to the building,
c) fans and other electrical equipment that are installed to maintain the air quality specified in Articles 3.2.6.2. and 3.3.3.6.,
d) fans required for venting by Article 3.2.6.6., and
e) fans required by Clause 3.2.8.4.(1)(c) and Article 3.2.8.7. in buildings within the scope of Subsection 3.2.6.”
Rule 46-202 of the CE Code states that when an emergency generator is used, it must comply with the CSA standard C282 “Emergency electrical power supply for buildings“
It is interesting to point out that notes (5) and (6) on the scope of C282 recognize use of standby/back up generators, as follows:
“1 Scope
1.1
This Standard applies to the design, installation, operation, maintenance, and testing of emergency generators and associated equipment for providing an emergency electrical power supply to electrical loads
-
- a) in buildings and facilities when the normal power supply fails and an emergency electrical power supply is required by the National Building Code of Canada (NBCC); and
- b) of essential electrical systems, where emergency generators are intended for use in health care facilities (HCFs) in accordance with Clause 6 of CSA Z32.
Notes:
1) For guidelines on emergency electrical power supply for life-support equipment, see Annex A.
2) In this Standard, the term “building” also includes facilities.
3) Normative provisions of this Standard are not limited to the installations where an emergency generator is used as the NBCC required emergency power supply source to the “life safety equipment”.
4) For guidelines on the use of emergency electrical power supply equipment for purposes beyond the provisions of Clause 1.1, see Annex D.
5) It is intended by the scope of this Standard that equipment other than “life safety equipment” could be connected to the emergency generator (see Clause 6.4.1).
6) For electrical power supply systems designed and installed to operate for purposes other than those specified in Clauses 1.1, the electrical power supply system should meet the requirements of this Standard, where practical, and in conjunction with the guidelines of Annex E.”
Question 2
Is a manual bypass switch required for a fire pump transfer switch?
Answer to question 2: Clause 9.5 of C282 states the following:
“9.5 Manual bypass switch
9.5.1
A means shall be provided to isolate and bypass automatic transfer switches that supply life safety equipment in buildings of Institutional Occupancy (Group B) and Residential Occupancy (Group C) classification, as defined by the NBCC, under the following conditions:
-
- a) the failure of an automatic transfer switch to transfer, when necessary, from a normal supply to an emergency supply;
- b) during maintenance or repair of the automatic portion of the transfer switch, the interruption of power during the isolation and bypass procedure does not exceed 15 s, and in the case of an HCF, 10 s;
- c) in buildings of Institutional Occupancy (Group B1 or B3) and Residential Occupancy (Group C) classification, as defined by the NBCC, with the bypass installed on the emergency side of the transfer switch; and
Note: A single-source bypass with the bypass on the emergency side is a minimum requirement and does not preclude the use of dual-source bypass switches with bypasses on both the emergency and the normal sides. See Clause B.21 for a discussion of necessary emergency bypass precautions and the advantages of a dual [1 source bypass.
-
- d) in buildings of Institutional Occupancy (Group B2) classification, as defined by the NBCC, with the bypasses installed on both the normal and emergency sides of the transfer switch.
Note: See Clause B.23 for commentary on this Clause.”
Requirements for a manual bypass switch are outlined in the CSA product standard for low voltage transfer switches, as specified in Annex D of C22.2 No. 178.1.
However, when a transfer switch is used for a fire pump service, in accordance with Rule 32-308 of the CE Code, this transfer switch must comply with the standards in Annex E of C22.2 No. 178.1, which does not mention a manual bypass switch for fire pump transfer switches. It is also notable that NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection, does not refer to manual bypass switches for fire pump transfer switches.
So, it is logical to assume that the requirement of Clause 9.5 of C282 is not intended to apply when an automatic transfer switch is used solely with a fire pump. The proposal to clarify this point in Clause 9.5 of C282 was recently submitted to the Technical Committee for C282.
Question 3
What is the difference between a grounding electrode and a station ground electrode?
Answer to question 3: “Grounding electrode” is a defined term, and the definition is provided in Section 0 of the CE Code, as follows: “Grounding electrode — a buried metal water-piping system or metal object or device buried in, or driven into, the ground to which a grounding conductor is electrically and mechanically connected.“ This definition is used throughout the CE Code more than 100 times, and Rule 10-102 of the CE Code mandates provisions for a typical grounding electrode used in every electrical installation, except for high-voltage installations, governed by Section 36 of the CE Code.
“10-102 Grounding electrodes (see Appendix B)
1) Grounding electrodes shall consist of
-
- a) manufactured grounding electrodes;
- b) field-assembled grounding electrodes; or
- c) in-situ grounding electrodes forming part of existing infrastructure.
2) Manufactured grounding electrodes shall
-
- a) in the case of a rod grounding electrode, consist of two rod electrodes
- i) spaced not less than 3 m apart;
- ii) interconnected with a grounding conductor sized as prescribed for grounding conductors; and
iii) driven to the full length of the rod;
-
- b) in the case of a chemically charged rod electrode, be installed to the full length of the rod; or
- c) in the case of a plate electrode, be
- i) in direct contact with exterior soil at not less than 600 mm below grade level; or
- ii) encased within the bottom 50 mm of a concrete foundation footing in direct contact with the earth at not less than 600 mm below finished grade.
3) A field-assembled grounding electrode shall consist of
-
- a) a bare copper conductor not less than 6 m in length, sized in accordance with Table 43 and encased within the bottom 50 mm of a concrete foundation footing in direct contact with the earth at not less than 600 mm below finished grade; or
- b) a bare copper conductor not less than 6 m in length, sized in accordance with Table 43 and directly buried in earth at least 600 mm below finished grade.
4) For the purposes of Rule 2-024, an in-situ grounding electrode shall not be considered electrical equipment and shall provide, at 600 mm or more below finished grade, a surface area exposure to earth equivalent to that of a similar manufactured grounding electrode.
5) Where a local condition such as rock or permafrost prevents a grounding electrode from being installed at the required burial depth, a lesser acceptable depth shall be permitted.”
Appendix B Note on Rule 10-102 clarifies that all components of a manufactured electrode are constructed to meet the requirements of CSA C22.2 No. 41, and Subrule 10-102(2) above elaborates on installation requirements for a typical manufactured electrode.
In high voltage installations, Section 36 mandates very specific requirements for a grounding electrode, and these requirements amend general provisions of Rule 10-102 of the CE Code in Rule 36-302(1), as follows:
“36-302 Station ground electrode (see Appendix B)
1) Every outdoor station shall be grounded by means of a station ground electrode that shall meet the requirements of Rule 36-304 and shall
a) consist of a minimum of four driven ground rods spaced at least the rod length apart and, where practicable, located adjacent to the equipment to be grounded
b) have the ground rods interconnected by ground grid conductors not less than No. 2/0 AWG bare copper buried to a maximum depth of 600 mm below the rough station grade and a minimum depth of 150 mm below the finished station grade; and
c) have the station ground grid conductors specified in Item b) connected to all non-current carrying metal parts of equipment and structures, and forming a loop around the equipment to be grounded, except that
i) a portion of the loop shall be permitted to be omitted where an obstacle such as a wall prevents a person from standing on the corresponding side or sides of the equipment; and
ii) loops formed by the rebar in a reinforced concrete slab shall be considered adequate when the rebar members are interconnected and reliably connected to all other parts of the station ground electrode.”
Although construction requirements for a typical grounding electrode must comply with the CSA standard C22.2 No. 41, Appendix B Note on Subrule Rule 36-302(1) offers the following clarification in this regard:
“Appendix B Bote on Rule 36-302 1) a)
Grounding rods are manufactured and certified to CSA C22.2 No. 41. It is intended by this Item that the designer of the station ground electrode will verify for each installation that the selected diameter and length of the ground rod are sufficient in order to comply with Rule 36-304.
The diameter may vary depending on the material chosen. The minimum diameter and length values should be used in preference to nominal values in the validation of compliance.”
As seen in Rule 36-302 above, Section 36 of the CE Code also uses different terminology than Rule 10-102, referring to this grounding electrode in a high voltage installation as a “station ground electrode.” It also provides specific terminology related to grounding in high voltage installations.
“Ground grid conductor — the horizontally buried conductor used for interconnecting ground rods or similar equipment that forms the station ground electrode.”
“Station — an assemblage of equipment at one place, including any necessary housing, for the conversion or transformation of electrical energy and for connection between two or more circuits.”
It should also be noted that Rule 36-308 mandates very specific requirements for connecting all non-current-carrying metal equipment and structures that are part of the station, as well as all metal items associated with the station, to the station ground electrode. This is to prevent the buildup of dangerous potential differences between the equipment or structures and the nearby earth. It is interesting to note that up to and including the 2012 edition of the CE Code, Rule 36-302 required a minimum length and diameter for ground rods of a station ground electrode, as follows.
“36-302 Station ground electrode (see Appendix B)
(1) Every outdoor station shall be grounded by means of a station ground electrode that shall meet the requirements of Rule 36-304 and shall
(a) consist of a minimum of four driven ground rods not less than 3 m long and 19.0 mm in diameter spaced at least the rod length apart and, where practicable, located adjacent to the equipment to be grounded;”
Afterward, all references to size were removed from the later editions of the CE Code, as Code users must use the standard dimensions for bonding and grounding equipment listed in C22.2 No. 41 “Bonding and grounding equipment,” whether the ground rods are installed according to Section 10 or are part of a station ground electrode as specified in Rule 36-302 of the CE Code.
The standard requires a solid iron or steel rod electrode to have a diameter of at least 15.8 mm.
Question 4
Is arc-fault (AFCI) protection of branch circuits supplying 125 V receptacles rated 20 A or less required for receptacles if receptacles are installed in a dormitory?
Answer to question 4: A dormitory is part of a suite, and a suite can include a dwelling unit, individual guest rooms in motels, hotels, boarding houses, rooming houses, and dormitories. A dwelling unit is a specific type of suite, as defined by the CE Code.
“Dwelling unit — a suite operated as a housekeeping unit that is used or intended to be used by one or more persons and contains cooking, eating, living, sleeping, and sanitary facilities (see Suite).”
CE Code also offers the following definitions of a suite:
“Suite — a single room or series of rooms of complementary use operated under a single tenancy, including dwelling units and individual guest rooms in motels, hotels, boarding houses, rooming houses, and dormitories.”
From the definitions shown above, it is clear that a typical dormitory serves as sleeping quarters for residents. A dormitory is meant to be a place where students who live at school sleep, and it is not considered a dwelling unit, as it does not include all the components listed in the definition of a dwelling unit (such as cooking, eating, or sanitary facilities).
Rule 26-658 of the CE Code is specifically written to require AFCI protection for each branch circuit supplying 125 V; 15 A or 20 A rated receptacles for dwelling units only, and this requirement does not include dormitories or single-room occupancies (see below).
“26-658 Arc-fault protection of branch circuits for dwelling units (see Appendix B)
Arc-fault protection of branch circuits for dwelling units shall meet the following requirements:
a) Each branch circuit supplying 125 V receptacles rated 20 A or less shall be provided with arc-fault protection by a combination-type arc-fault circuit interrupter, except for branch circuits supplying
i) receptacles installed in accordance with
A) Rule 26-720 f), provided that no other receptacles are connected to these circuits; or
B) Rule 26-722 d) i), iii), iv), and v); and
ii) a single receptacle for a sump pump where
A) the receptacle is labelled in a conspicuous, legible, and permanent manner identifying it as a sump pump receptacle; and
B) the branch circuit does not supply any other receptacles.
b) Notwithstanding Item a), the entire branch circuit need not be provided with arc-fault protection where
i) an outlet branch-circuit-type arc-fault circuit interrupter is installed at the first outlet on the branch circuit; and
ii) the wiring method for the portion of the branch circuit between the branch circuit overcurrent device and the first outlet consists of metal raceway, armoured cable, or non-metallic conduit or tubing.
c) Where one or more 125 V receptacles rated 20 A or less are added to an existing branch circuit that is not provided with arc-fault protection as required by this Rule, the entire branch circuit need not be provided with arc-fault protection where an outlet branch-circuit-type arc-fault circuit interrupter is installed at the first added receptacle to the existing branch circuit.“
A history of AFCI protection mandated by the CE Code is quite interesting. Until the 2015 edition of the Code, such protection was only required for branch circuits supplying receptacles installed in sleeping areas of a dwelling unit (see paragraph 26-722(f) of the 2012 edition of the CE Code).
“26-722(f) branch circuits that supply receptacles installed in sleeping facilities of a dwelling unit shall be protected by an arc-fault circuit interrupter.”
However, even in the current edition of the CE Code, published in 2024, Rule 26-658 shown above, allows for numerous exceptions to this requirement, and there have been several proposals to Section 26 S/C requesting an increase in the number of such exemptions due to the frequent tripping of the combination type AFCIs.
It should be noted that under provisions of Article 210.12 in the National Electrical Code (NEC), this AFCI protection requirement is extended to the branch circuits supplying outlets in dormitory units and in guests rooms/guest suites.
Question 5
Is a unit substation a single piece of equipment?
Answer to question 5: A typical unit substation is an integrated assembly consisting of different pieces of “approved” (certified to the applicable CSA safety standards) electrical equipment.
Rule 26-240(1) of the CE Code defines a unit substation as follows:
“26-240 Transformers — General (see Appendix B)
1) In this Subsection,
a) “transformer” shall mean a single-phase transformer, a polyphase transformer, or a bank of two or three single-phase transformers connected to operate as a polyphase transformer; and
b) “unit substation” shall mean an integrated unit consisting of one or more transformers, disconnecting means, overcurrent devices, and other associated equipment, each contained in a suitable enclosure designed and constructed to restrict access to live parts.”
For example, a unit substation is typically assembled by an electrical equipment manufacturer based on shop drawings, and such integrated assembly can be constructed either at the factory or on-site at the intended installation location.
Interconnection of equipment within a unit substation is not subject to an electrical installation permit or inspection by the electrical safety AHJ for compliance with the CE Code, because this integrated assembly functions as a single unit of these individual pieces of electrical equipment, each certified to different CSA safety standards.
Thus, a typical high voltage switch that becomes a component of such an integrated assembly would need to be designed, constructed, tested, and certified to the CSA standard C22.2 No. 193 “High-Voltage Full-Load Interrupter Switches.” Similarly, a dry-type transformer must be designed, constructed, tested, and certified to the CSA standard C22.2 No. 47 “Air-cooled transformers,” and a low voltage switchgear should be certified to the CSA standard C22.2 No. 31 “Switchgear assemblies.”
As the AHJ would not have means to evaluate safety and reliability of interconnection between these various pieces of electrical equipment comprising the unit substation, the AHJ would accept installation of such integrated assembly, when upon completion of the field assembly and prior to a request for an electrical inspection, the electrical equipment manufacturer responsible for the assembly of the unit substation in accordance with the shop drawings, makes an arrangement for approval of the complete integrated assembly by means of a field evaluation/special inspection in conformance with SPE 1000 “Model Code for the field evaluation of electrical equipment.”
Such field evaluation (”approval”) must be conducted by a specialized inspection body accredited by the Standards Council of Canada, provided that the inspection body is recognized by the AHJ. (see Appendix B Note of the CE Code on the definition of “approved” equipment)
“Appendix B Note on definition “approved”
This definition is also intended to reflect the fact that equipment approval could be accomplished via a field evaluation procedure in conformance with CSA Model Code SPE-1000 or, for medical electrical equipment, CSA Model Code SPE-3000, where special inspection bodies are recognized by participating provincial and territorial authorities having jurisdiction. For new products that are not available at the time this Code is adopted, the authority having jurisdiction may permit the use of products that comply with the requirements set out by that jurisdiction.”
Question 6
What is the difference between a switchboard and switchgear?
Answer to question 6: A switchboard and switchgear are parts of distribution equipment, and they serve a similar purpose according to the CE Code.
Switchgear is built and designed for both high and low voltage installations.
Switchboards are rated for voltages up to 600 V or less.
A switchgear consists of various switching devices that control, protect, and isolate power systems.
A switchboard is a part of an electrical distribution system that divides electrical power into feeders and branch circuits, while also providing a protective circuit breaker or fuse for each circuit within a single enclosure.
A switchgear and a switchboard may serve as service entrance or distribution equipment, but their electrical characteristics, ratings, design, construction, and application are quite different.
The term “switchgear” is used in the CE Code 36 times, but the CE Code does not define this term.
The term “switchboard” is used in the CE Code 44 times, and the CE Code offers the following definition of the switchboard:
“Switchboard — a panel or assembly of panels on which is mounted any combination of switching, measuring, controlling, and protective devices, buses, and connections, designed to successfully carry and rupture the maximum fault current encountered when controlling incoming and outgoing feeders.”
A typical switchgear is designed, constructed, and certified to the CSA standard C22.2 No. 31 “Switchgear assemblies”, and this safety standard offers the following definitions for switchgear:
“Low-voltage, metal-enclosed, air circuit breaker switchgear — a switchgear assembly for service up to nominal voltages of 600 V ac and 750 V dc, containing air circuit breakers, buses, and connections, with an enclosure on the sides, back, top, and front.
Note: The air circuit breakers are contained in individual compartments and controlled remotely or from the front panels. The structures are of two types, stationary and draw-out, as follows:
a) the stationary type contains air circuit breakers that are mounted on bases and have no special arrangement for quick removal from the structure; and
b) the draw-out type contains air circuit breakers so arranged that they can be easily drawn out of the structure and easily disconnected from the buses through self-coupling devices.”
“Metal-clad switchgear — a specific type of metal-enclosed switchgear. It is a metal structure containing switching equipment and other associated equipment such as instrument transformers, buses, and connections. The circuit breakers, transformers, buses, and connections are placed in separate, grounded, metal compartments, which are either unfilled (dry type) or contain a liquid, semi-liquid, or other insulating medium.
Note: The circuit breaker is equipped with self-coupling disconnecting devices and is arranged with a position[1]changing mechanism for moving it physically (through either vertical or horizontal travel) from the connected position to the test or disconnected position, after which it may be removed from the stationary structure, or vice versa. Interlocks are provided to ensure proper sequence and safe operation.”
“Metal-enclosed (or cubicle) switchgear — a switchgear assembly enclosed on all sides and top, which may have the control, meter, and protective equipment mounted at the front or back, and the fixed primary switching devices with related equipment, including buses where required, located inside.
Notes:
1) The primary switching devices are not necessarily provided with self-coupling disconnecting devices.
2) The primary switching devices may be located in a compartment separated from the secondary and control wiring and devices.“
This CSA standard applies to electrical equipment with a nominal voltage of up to 46 kV intended for use in non-hazardous locations, for controlling and protecting power from generators or other sources, and for supplying electrical energy to power and lighting circuits.
It applies to dead-front indoor and outdoor enclosed assemblies of various equipment parts that make up the switchgear, such as switches, air and power circuit breakers, control and metering equipment, along with associated interconnections and supporting structures.
A switchboard is designed, constructed, tested, and certified according to the CSA standard C22.2 No. 244 “Switchboards.” This standard is harmonized between Canada, Mexico, and the USA.
The scope of this standard states the following:
“1.1.1 This Standard applies to switchboards nominally rated at 600 V or less and intended for use in accordance with the Canadian Electrical Code, Part 1 (CE Code, Part 1), the National Electrical Code (NEC), ANSI/NFPA 70, and the Mexican Standard for Electrical Installations (Utility), NOM-001-SED
1.1.2 In this standard the term switchboard is intended to refer to a dead-front switchboard.
1.1.3 These requirements do not cover the following switchboard types: preset and dimmer control (theater), live front, railway control or electrification; or constructions intended only for receiving motor control center units.
1.1.4 These requirements cover switchboards for use on circuits having available rms symmetrical short-circuit currents of not more than 200 000 A.”
Electrical consultants should familiarize themselves with the safety standards for both types of equipment and understand the differences between the relevant electrical characteristics of a switchgear and a switchboard—to determine whether a switchgear or a switchboard is more suitable for a specific installation.
And as usual, a local AHJ should be consulted regarding the CE Code compliance when applying a switchgear or switchboard for a specific installation.
Ark Tsisserev is president of EFS Engineering Solutions, an electrical and fire safety consulting company, and is a registered professional engineer with a master’s degree in Electrical Engineering. Prior to becoming a consultant, Ark was the Chief Electrical Inspector for the City of Vancouver. He is the immediate past chair of the CSA TC for the CE Code, Part I, and for the CSA Strategic Steering Committee for the Requirements of Electrical Safety. Ark also represents the CE Code Committee on the CMP-1 of the National Electrical Code. Ark can be reached by e-mail at ark.tsisserev@efsengineering.ca. His company website is www.efsengineering.ca.
